The present invention relates generally to fluid reservoirs, and more particularly to a reservoir for the hydraulic fluid of an automobile braking system. More specifically, the invention relates to a detection device for signalling a low level of brake fluid within the reservoir.
Systems utilizing the pressure of a hydraulic brake fluid are widely used in automotive braking devices. In such systems, a master cylinder having a piston which is actuated by a force applied on the brake pedal of the vehicle operates as the hydraulic pressure generating source. Proper operation of the braking system and, consequently, safety considerations in the operation of the vehicle, depend upon the presence of a sufficient level of hydraulic fluid within the braking system. Accordingly, means are usually provided for determining the level of the braking fluid within a liquid reservoir of the braking system which is usually provided as part of the master cylinder. More particularly, such means must operate to issue a warning signal when the fluid level within the master cylinder reservoir drops below a required level for safe and effective operation.
In one known prior art system, a reservoir tank containing the hydraulic brake fluid includes a float mechanism operating to sense the level of the braking fluid within the reservoir. This system utilizes a reed switch to signal a low level of hydraulic fluid in accordance with the position of the float. When, in such a system, the fluid level within the reservoir tank drops to a predetermined position, the reed switch is actuated by magnetic means contained within the system and a signal is generated by an external signal device to indicate that the brake fluid must be replenished.
However, in such a device, the liquid phase portion and the vapor phase portion of the reservoir are not separated. Thus, moisture in the atmospheric air may be absorbed by the brake fluid. This gives rise to several problems including, for example, lowering of the boiling point of the brake fluid.
Thus, it has been found advantageous to maintain the liquid portion and the vapor portion of the brake fluid reservoir separated. Efforts to provide a structure involving separated liquid and vapor portions have, however, encountered substantial difficulty. First, the presence of a reed switch holding tube substantially at the center of the reservoir and the necessity for a float responsive magnet for actuating the reed switch, have caused space problems. Accordingly, with presently known structures, it has been difficult to overcome the problems involved in separating the liquid portion from the vapor portion of the brake fluid reservoir without introducing other disadvantages.
The present invention is directed toward overcoming the problems which arise when the liquid portion and the vapor portion of a brake fluid reservoir tank are not partitioned. In accordance with the present invention, means are provided for partitioning the reservoir to overcome the aforementioned difficulties without introducing other attendant problems.